Various kinds of electric power equipment including wheels for propelling the electric power equipment and a work unit for performing a prescribed work are known in such forms as lawn mowers, snow blowers and tillers. See JPH09-201126A, JP2016-156223A and JP2009-296933A, for instance. Such electric power equipment is typically provided with wheels to propel the equipment, and the work unit performs the prescribed work as the equipment travels forward. The work unit may cut the grass, remove the snow or till the soil depending on the particular application.
In such electric power equipment, the rotational speed of the motor (work motor) for the work unit is usually maintained at a constant value so that an optimum result may be obtained for the given power of the work motor that drives the work unit. However, the load of the work unit may vary for each particular area that is being worked. For instance, in the case of a lawn more, the grass may be taller and/or more dense in some part of the lawn than in other parts. When the load changes, the rotational speed of the rotary blade changes. If the blade rotational speed is excessively low, the grass may be torn or ripped, and this causes an uneven unattractive finish.